Well, not many people own an ECS K7VTA3, so not many will be able to tell you of its reliability. I built a system for my dad using one, and he's been running it 24/7 since early May without any problems. The only crashes and reboots that happened were because of overclocking/heating problems. At default speeds, the system never needed a reboot until I applied a WindowsUpdate or something similar that required a reboot.
At its price(at least over here, where its barely costs more than a K7S5A and less than a K7S6A or other SiS745 mobos), ECS hit a bullseye at the budget market that doesn't do hardcore overclocking. If you're looking for a motherboard for hardcore overclocking, look elsewhere - this isn't the motherboard to get, with its lack of 1MHz FSB speeds, voltage or multiplier settings. However, its a real gem for its price, and even has some admittedly limited FSB speeds other than the default 133/166MHz settings.
For more info on the system I have built around the K7VTA3, you can look at my system rigs.
As for the motherboard plate...I'm not sure if the L7VTA uses a new design, but even if it does, it will probably come with a compatible plate. All motherboards that I know of ship with compatible plates.
btw ECS is also known as EliteGroup, and used to produce the notorious PCChips(spelling?) that were pretty much execrable, but ever since the K7S5A their products have been more popular...they're definitely not tier 1, maybe not even tier 2, but I've found them to be pretty reliable, consistent and good performing for their extremely low price.